Magnetic coil



May 10,1927. 1,628,398

w. L.. CASPER ET AL MAGNETIC COIL Filed June 6, 1922 @my ma@ by j# im,Wy

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Patented May 10, 1927.

VUNITED STATES PATENT OFFICE.

WILLIAM L. CASPER, OF BROOKLYN, NEW YORK, AND FRANK E. FIELD, OF SOMER-VILLE, NEW JERSEY, ASSIGNORS TO WESTERN ELECTRIC COMPANY, INCOR-PORATED, OF NEW YORK, N. Y., A CORPORATION 0F NEW YORK.-

MAGNETIC COIL.

Application filed June 6, 1922. Serial No. 566,421.

This invention relates to magnetic coils and particularly totransformers for tele phone currents and the like.

An object of the invention is to provide for readily adjusting themagnetic reluctance of a magnetic coil.

Another object 0f the' invention is to provide 1n a magnetic coil havinga` Winding traversed by direct current, a magnetic circuit Which is verysensitive to alternating current to be transmitted, but relativelyinsensitive to changes in' direct current.

The invention further resides in various details of the coil supportingbracket or casing and in the structure and arrangement of the electricalterminals.

In one embodiment of the invention, a laminated shell type core isemployed comprising an E-shaped section anda straight or I-shapedsection. The Winding or windings surround the middle leg of the core,and a mounting bracket is employed comprising a housing which embracesthe remaining portion of the core. `The housing may be of a single pieceof sheet metal or of a plurality of' portions. In either case itcomprises means for exerting a desired amount of lateral pressure on thecore so as to vary the magnetic gaps between the sections. It has beenfound that where dire-ct current flows through one of the windings, anair gap is desirable in order to prevent saturation of the core.Convenient means is provided by this invention for Varying the gap so asto obtain maximum efficiency in the transmission of alternatingcurrents, such as Voice currents.

Referring to the drawings:

Fig. 1 is a side elevation of one embodiment of the invention;

Fig. 2 is a front elevation partly broken away;

Fig. 3 is a plan View, partly broken away, of the form shown in Fig. 1;

Figs. 4, 5, and 6 are views similar to Figs. 1, 2, and 3 of another formof the invention' Fig. 7 is a detailed view of a terminal ernployed inthe form shown in Fig.. 4.

Fig. 1 shows a transformer having a laminated core 10 comprising anE-shaped sec-y tion 12 and an I-shaped section 14. The laminations arepreferably secured together by rivets, as shown at 16. The transformerwindings 17 surround the central limb 18 of the core section 12. Acasing or mounting bracket 2O is formed of a single sheet of metal bentso as to embrace the top and faces of the core. Openings 22 are providedin the sides of the casing through which the windings 17 project. At oneside of' each open1ng'22 the metal is bent out to form a flange 24carrying the terminal pieces 26. As shown in Fig. 3, each terminal 26iis mounted in an insulating bushing 28. While four terminals are shown,the flanges 24 are obviously adaptable for mounting any desired numberof terminals. At the edges of casing small flanges or tabs 30 are bentinwardly and by suitable means, such as a press, are forced against theedges of the core members 12 and 14 so as to establish the desiredamount of pressure on the abutting surfaces of the core sections. Thesurfaces are preferably plane and in most cases are in direct contactwith each other, although under some conditions it may be desirable tointerpose a sheet of paper or other material to assist in regulating themagnetic gap. The lower edges of casing 2O are bent outwardly to formflanges 32 adapted for attachment to a support.

The core of the transformer shown in Figs. 4, 5, and 6 is similar tothat shown in Fig. 1. The casing or mounting bracket differs, however,in that it comprises two channel-shaped members 34 embracing the sidesof the core. The channel members 'have inwardly extending end flanges 36and 38, andvat each inner edge adjacent the winding 17, a pair of ears40. Bolts 42 pass through ears 40 ad serve the function of drawing thechannel members toward each other and exerting pressure on the abuttingsurfaces of the core sections. Bolts 42 also serve to secure in positionterminal plates 44, preferably made of insulating material. Mounted onterminal strip 44 are terminal pieces 46, one of Which is shown indetail in Fig. 7. An eyelet 48, passing through opening 50, secures theterminal `pieces to the plate 44. Terminal piece 46 is also providedwith a projection 52 extending into a recess 53 and with angularextensions 54 and 55 to which electrical conductors may be soldered.

A name plate 56 of aluminum or the like may be secured in positionbetween flanges 36 and the core. Outwardly extending flanges 58 areprovided at the lower end of channel members 34 for attachment to asupport. Any suitable lining may be provided between the core and itscasing or bracket, if desired.

While only two forms of the invention have been shown and described, itis to be understood that the invention is entitled to a reasonable rangeof e uivalents wjthin the scope ot' the appended c aims.

'lllc invention claimed is 1. A magnetic coil having a core comprising aplurality of layers of magnet-ic material, each layer comprising aplurality of sections, a frame comprising channel-shaped membersembracing said sections, a terminal plate associated with said membersand means for drawing said members toward each other and .securing saidterminal plate in position.

2. A magnetic coil having a core comprising a plurality of layers ofmagnetic material, cach layer comprising a plurality of sections, aframe comprising a pair ot channel-shaped members embracing saidsections, perforated ears on said members, a terminal plate interposedbetween said members and bolts passing through the perforations fordrawing said members together and securing said terminal plate inposition.

3. A magnetic coil comprising a shelltype core, a winding on the middlebranch of said core, a casing having the form of a frame closelyembracing the remaining portion of said core, a plate carried by saidcasing adjacent said winding and lying in a plane transverse to that ofsaid core, and terminals mounted on said plate.

4. A magnetic coil comprising a plurality of laminated core sections, aframe cbmprising a pair of channel-shaped members embracing saidsections, perforated ears on said members, bolts passing through theperforations for drawing said members together, a plate of insulatingmaterial secured to one of said ears, and terminals mounted on saidplate.

5. A magnetic coil comprising a rectangular core, channel membersembracing two sides of said core, said members having portions turnedinwardly at their ends for embracing the ends of said core and havingperfo 'ated portions turned outwardly, and bolts passing through saidperforated portions t'or drawing said members toward each other.

6. A magnetic coil comprising a shell-type core, a winding on the middlebranch ofsaid core, a casing having the form of a frame closelyembracing the remaining portion of said core an insulated terminal platecarried by said casing and lying in a plane transverse to that of saidcore, and terminals mounted on said plate and connected to saidv

